Process for removing water from a borehole using polymeric foaming agent

ABSTRACT

An improved process for removing water from boreholes and the like comprising using as a foaming agent a copolymer of acrylamide and diacetone acrylamide.

United States Patent Inventor Appl. No.

Filed Patented Assignee Leonard John Persinski Pittsburgh, Pa.

Sept. 28, 1970 Dec. 28, 1971 Calgon Corporation Pittsburgh, Pa.

PROCESS FOR REMOVING WATER FROM A BOREHOLE USING POLYMERIC FOAMING AGENT4 Claims, No Drawings US. Cl 166/309, 175/71, 252/356 Int. Cl E21b 21/00Primary Examinerlan A. Calvert Att0rneysWilliam L. Krayer and Herbert J.Zeh, Jr.

ABSTRACT: An improved process for removing water from boreholes and thelike comprising using as a foaming agent a copolymer of acrylamide anddiacetone acrylamide.

PROCESS FOR REMOVING WATER FROM A BOREHOLE USING POLYMERIC FOAMING AGENTBACKGROUND OF THE INVENTION This invention is directed to an improvedprocess for removing water from oil wells, gas wells and otherboreholes. More particularly, this invention is directed to the use of acopolymer of acrylamide and diacetone acrylamide as a foaming agent tofacilitate the removal of water from boreholes with air or other gaseousfluids.

It has become the common practice in the art to use foaming agents toremove water from boreholes during air drilling operations. The foamincreases the rate at which water can be carried to the surface by theair or other gaseous fluid. Heretofore, the most widely used foamingagents were soaps, detergents and the like. However, these compoundswere not as effective as desired nor as economical as desired. Morerecently, high molecular weight water-soluble natural and syntheticpolymers have been utilized in conjunction with soaps and the like asfoaming agents. For example, see US. Pat. No. 3,251,417. However, whilethese polymers do create a foam for removing water, they are not aseffective as desired. It has therefore become necessary in manyoperations to discontinue the use of air or gas and resort to siphoningor pumping out the water or to circulating a conventional drilling mud.

SUMMARY OF THE INVENTION 1 have found that the efficiency of waterremoval in air drilling and similar operations can be improved byutilizing as a foaming agent a copolymer of acrylamide and diacetoneacrylamide. The polymers of my invention increase foam production andprovide a stable foam thereby increasing the rate at which water can beremoved to the surface.

The polymers of my invention are random, linear, watersoluble copolymersof acrylamide and diacetone acrylamide. The polymer composition is from5 to 60 percent by weight diacetone acrylamide and from 40 to 95 percentby weight acrylamide. The acrylamide portion of the polymer may behydrolyzed such that up to 65 percent of the amide groups originallypresent are converted to carboxylic acid groups or carboxylate saltgroups. The polymer has the structural formula illustrated below -CGH,CHGHQ-CH ICHT-CEMAM 5:0 91:0) 1 (1:0 +11 I'iH, 5 M

where x is from 5 to 60 percent by weight, the sum of y plus 1 is from40 to 95 percent by weight and z is from 0 to 65 percent of the sum of yplus z and where M is selected from the group consisting of hydrogen,alkali metal and ammonium.

The actual composition of the polymeric foaming agent utilized incarrying out the invention will depend upon the particular compositionof the water to be removed and the condition under which the water isremoved. As is realized by one skilled in the art, a different polymericfoaming agent would be desired for removing brackish water than forplain well water. Therefore, the preferred polymer composition of myinvention will ultimately depend on the characteristics of theindividual application and will be a balance between the amount ofdiacetone acrylamide in the polymer and the amount of hydrolysis.

The polymers of my invention have all the essential characteristicsnecessary for an efficient water removal operation. The polymers arestable at the elevated temperatures found at the bottom of boreholeswhich may reach as high as 300 F. or higher. They are stable in brineand are nonprecipitating in the presence of the inorganic salts oftenfound in the water that has to be removed. Finally, the polymers of myinvention produce a very stable foam at relatively low concentrations.

The basic composition of the polymers of this invention have beendisclosed by Coleman in US. Pat. No. 3,277,056. The use of these typesof polymers as friction reducers is shown in U.S. Pat. No. 3,451,480,and the use of them in secondary oil recovering processes is shown in mycopending application Ser. No. 842,349, filed July 16, 1969, entitledPolymers for Waterflooding.

The polymers useful in my invention may be prepared by copolymerizingdiacetone acrylamide and acrylamide in the desired ratio and thenhydrolyzing the acrylamide moiety to obtain the desired amount ofcarboxylic functionality. The scope of this invention is independent ofthe polymerization technique and the hydrolysis technique used. One ofordinary skill in the art understands the various applicable techniquesand would be able to prepare the appropriate compositions useful in myinvention.

The polymers of my invention may have a wide range of molecular weights.The polymers will normally have a molecular weight ranging between10,000 and 10,000,000 or higher. The molecular weight that is mosteffective will depend on the amount of diacetone acrylamide in thepolymer and on the amount of hydrolysis of the acrylamide. In mostcases, it is preferred that the polymer have a molecular weight inexcess of 100,000.

My polymeric foaming agents will produce a utilizable foam when presentin the water at concentrations of at least about 50 p.p.m. by weight,preferably 100 p.p.m. or more. The maximum concentration will largely bedetermined by economic considerations. However, for all practicalpurposes, a concentration greater than 1,500 p.p.m. will never be used.As is realized by one skilled in the art, the exact concentrationemployed will depend on the characteristics of the water being removed,the conditions under which it is being removed and the particularpolymer being utilized.

A series of polymers were prepared containing various amounts ofdiacetone acrylamide and acrylamide. The polymers of each series werethen hydrolyzed to various percentages. The resulting polymers wereevaluated for properties that are desirable in effective foaming agentsfor water removal. The following tables illustrate the compositions ofthe polymers and the results of these evaluations.

TABLEl Hydrolyzed DAA Content Acrylamide Acrylamide Polymer Weight Molein Mole Units in Designation Percent Percent Percent Mole k 0 DAA 0 0 0I00 0 0 DAA l0 0 0 90 10 0 DAA 20 0 0 20 0 DAA 40 0 0 60 40 5 DAA 0 52.13 97.87 0 5 DAA l0 5 213 87.87 [0 5 DAA 20 5 2.13 77.6 20 S DAA 30 5213 67.87 30 S DAA 40 5 2.13 57.87 40 30 DAA I0 30 I6 74 I0 30 DAA 20 30I6 64 20 3O BAA 30 30 I6 54 30 30 DAA 40 30 16 44 40 5O DAA 0 50 29.670.4 0 50 DAA 10 50 29.6 60.4 10 50 DAA 20 50 29.6 50.4 20 50 DAA 30 5029.6 40.4 30 S0 DAA 40 50 29.6 30.4 40 6O DAA 0 60 38.6 61.4 0 60DAA I060 38.6 5L4 I0 60 DAA 20 60 38.6 4L4 20 60 DAA 30 60 38.6 31.4 30 60 DAA40 60 38.6 21,4 40

Temperature Stability Solutions of the polymers containing 1 gram ofpolymer per liter of distilled water were prepared. The viscosities ofthe solutions were measured using a Fann viscometer, model 35, at 73 F.and after being held for 24 hours at 172 F. The readings were taken at100 r.p.m. The results are shown in table 2.

The results in table 2 show that the polymers of my invention are stableat the elevated temperatures encountered in many drilling operations.

Salt Stability Solutions of the polymers containing 1 gram of activepolymer per liter of distilled water were prepared. The viscosities ofthe solutions were measured using a Fann viscometer at 72 F. and 300r.p.m. Increments of various salts were added and the viscosity measuredafter each increment. The salts used were CaCl NaCl, and KC]. Theresults are shown in tables 3, 4, and 5.

TABLE 3 Efiect ofCa Polymer Ca in p.p.m. p. in cps.

DAA 20 I00 5.8 5 DAA 30 I00 8.2 30 DAA 30 I00 7.8 0 DAA S00 3.4 5 DAA 30500 2.6 30 DAA 30 500 2.6

O DAA 20 900 2.9

5 DAA 30 900 L8 30 DAA 30 900 2.0 0 DAA 20 [.300 2.7 5 DAA 30 L300 [.430 DAA 30 L300 L8 0 DAA 20 2,300 2.5 S DAA 30 2.300 1.4 30 DAA 30 2,300L6 TABLE 4 Effect of NaCl Polymer NaCl in p.p.m. p. in cps.

0 DAA 20 I00 11.2 5 DAA 30 I00 I04 30 DAA 30 I00 12.0 0 DAA 20 500 7.6 5DAA 30 500 6.0 30 DAA 30 500 7.2 0 DAA 20 900 6.6 5 DAA 30 900 4.4 30DAA 30 900 5.6 0 DAA 20 L700 56 5 DAA 30 1,700 3.2 30 DAA 30 1.700 4.2 0DAA 20 4.500 4.4 5 DAA 30 4.500 2.0 30 DAA 30 4.500 2.6

TABLE 5 Effect of KCl Polymer KCI in p.p.m. p. in cps.

0 DAA 20 I00 ".6 l5 DAA 30 [00 13.0 50 DAA 30 [00 25.0 0 DAA 20 500 8.415 DAA 30 500 8.6 50 DAA 30 500 l7. 0 DAA 20 900 7.3 l5 DAA 30 900 6.850 DAA 30 900 14.2 0 DAA 20 L700 6.2 l5 DAA 30 [.700 5.0 50 DAA 30 [.70010.8 0 DAA 20 4.500 4.8 l5 DAA 30 4,500 3.2 $0 DAA 30 4,500 6.8

The results in tables 3, 4, and 5 show that the polymers are stable inthe presence of high electrolyte concentrations. Moreover, it shouldalso be noticed that the polymers did not precipitate in the presence ofthese electrolytes. This is an important characteristic since the brinesencountered in most drilling operations contain anywhere from a fewparts per million to several percent of dissolved salts.

Surface Activity Solutions of the polymers containing 250 p.p.m. ofactive polymer in distilled water were prepared. The surface tension wasmeasured using a duNouy Tensiometer. Results are shown in table 6.

The results in table 6 show the effect of increasing diacetoneacrylamide on surface activity. The diacetone acrylamide imparts surfaceactivity to the polymer and surface activity is an important property ofan effective foaming agent.

Water Removing The foaming tendency of the polymers of my invention wasobserved during the preparation of the polymer solutions for evaluationin tables 2 through 6 above. The foam produced during these tests wasvoluminous and tenacious. The water removing ability of the polymers wasinvestigated in the following manner. A glass column, 1 inch in diameterand 42 inches in length was fitted with a gas bubbler connected to anair supply. Three hundred milliliters of tap water was added to thecolumn. The water removing agent was then introduced and observations ofits effectiveness made and recorded. Table 7 illustrates the results forone of the polymers of my invention.

TABLE 7 Concentration Percent Compound Tested Used in p.p.m. H,0 RemovalNonylphenoxypoly (ethyleneoxy) ethanol 50 60 O DAA 50 300 97 I claim:

1. An improved process for removing water from a borehole to the surfacecomprising adding a foaming agent to the water and passing a gas throughthe water to generate foam and lift the foam to the surface wherein theimprovement comprises using as the foaming agent a water-soluble,linear, high molecular weight polymer of 5 to 60 percent by weightdiacetone acrylamide and 40 to percent by weight acrylamide wherein upto 65 percent of the amide groups of the acrylamide are hydrolyzed tocarboxylic groups.

2. Method of claim 1 wherein the polymer is used at a concentration ofat least 50 p.p.m. by weight.

3. Method of claim 2 wherein the polymer has a molecular weight of atleast 10,000.

4. Method of claim 1 wherein the polymer has a molecular weight of atleast 10,000.

UNITED STATES PATENT OFFICE I CERTIFICATE OF CORRECTION Patent No. 3,630,286 Dated December inventofls) Leonard John Persi It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Column 1, line 45, in the formula section "3'", the double bond between"the, carbon and nitrogen in the acrylamide should be a single bond.

Column 2, Table 1, between 5 DAA and 3mm 10, the following DAA seriesand 30 DAA 0 should be inserted:

15 DAA 0 15 6.93 93.17 0 j 15 DAA 10 15 .93 83.17 10 15 DAA '15 0.9373.17 5 2o 15 DAA 15 6.93 63.17 30 15 DAA 40 15 6.93 53.17 40 3O DAA O30 1 6 84 O.

Signed and sealed this 12th day of Decerfiber 1972.

(SEAL) Attest:

EDWARD M.FLEI'CHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents FORM PO-O (10-69) USCOMM-DC 6O376-P69 & u,s. GOVERNMENTPRINTING orncz: I989 0-368-334.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION 7 Patent: No. 3,630,286 I Dated December 971 Leonard John Persineki Inventor(s) It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 1, line #5, in the formula section "y", the double bond between"the carbon and nitrogen in the acrylamide should be a single bond.

Column 2, Table 1, between 5 IDAA L0 and 3 DAA 10, the following 15 DAAseries and 30 DAA 0 should be inserted:

15 DAA 0 15 6.93 93.1? o' 15 DAA .93 83.17 10 15 DAA 15 0.93 73.17 20 15DAA 15 6.93 '63. 17 30 15 DAA 40 15 6.93 53.17 40 30 DAA 0 30 16 84 0.

Signed and sealed this 12th day of Decerfiber-l972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Atteeting Officer 1 Commissionerof Patents FORM po'wso 069T uscoMM-bc 60376-P69 [1.5. GOVERNMENTPRINTING OFFICE: I969 3B-33"

2. Method of claim 1 wherein the polymer is used at a concentration ofat least 50 p.p.m. by weight.
 3. Method of claim 2 wherein the polymerhas a molecular weight of at least 10,000.
 4. Method of claim 1 whereinthe polymer has a molecular weight of at least 10,000.